Electrocinética

Electrocinética is a field that studies how electric fields influence the movement of fluids and charged particles in liquid media, and how fluid motion conversely generates electric responses in charged systems. It covers transport phenomena that arise from the coupling of electrostatics and hydrodynamics at solid–liquid interfaces, typically in electrolytes.

The main phenomena include electrophoresis, the motion of dispersed charged particles under an applied electric field; electroosmosis, the bulk movement of liquid through a capillary or porous wall due to a stationary surface charge when an electric field is applied; and streaming potential, an electric voltage produced by pressure-driven flow through a channel or porous medium. Dielectrophoresis, the movement of neutral but polarizable particles in nonuniform electric fields, is often treated within related electrokinetic frameworks. Electrokinetic effects are central in microfluidics and nanofluidics, enabling pumping, mixing, separation, or deposition without moving parts.

Theoretical description typically couples fluid dynamics with electrostatics. In many contexts, viscous, incompressible flow is described by the Navier–Stokes equations augmented with an electric body force term derived from the local charge density and electric field; the electric potential and charge distribution are described by Poisson–Boltzmann or related models for the electric double layer. Key quantities include the Debye length and the zeta potential, which characterize the interfacial region where electrostatic forces act.

Applications include microfluidic lab-on-a-chip devices, capillary electrophoresis, electrokinetic deposition, electroosmotic pumps, and in environmental engineering for soil and groundwater remediation. Measurements often rely on electrophoretic mobility, streaming current and potential, and zeta-potential analysis.